Packages that explode when dropped, cows that unexpectedly turn fertile, hands that sprout hair, and little boys who pull chairs out from under old ladies are the foundation of the American legal profession. Every student in every law school in the land learns his or her trade by studying a body of true cases that often seem the stuff of Rube Goldberg drawings but that are invaluable for vividly illustrating basic elements of the law.

Case study was invented by Christopher Columbus Langdell, dean of the Harvard Law School, in 1870. Previously, law had been taught mainly through lectures; since then, students have learned fundamental principles through real applications, exploring judges’ decisions and opinions in tough classroom question-and-answer sessions. The cases they study do not, by and large, involve events of any historical importance; rather, they are cases that, according to the authors of one classic casebook, are “vivid, teachable and provocative.” They go right to the heart of frequently applied principles of law, they contain interesting treatments of these points as brought out in judges’ opinions, and, of equal importance, they are memorable. In the words of Charles Rembar, a practicing attorney who wrote The Law of the Land and The End of Obscenity, professors choose cases that will “keep the students awake.”

What follow are five such cases, startling classics that are known to lawyers and law students all across the land—and to almost nobody else.

Hiram Walker & Sons contracted to sell a supposedly infertile Black Angus named Rose 2d of Aberlone to T. C. Sherwood. Rose then became pregnant. Because a fertile cow is worth vastly more than a barren one, Walker refused to deliver her. Sherwood sued for Rose and won. Walker appealed and lost and then appealed again, to the Michigan Supreme Court. The court granted a new trial.

In all these cases, the basic text for study is an appellate court’s ruling—specifically, the court’s discussion, in its written opinion, of how a lower court did or did not correctly apply the law. Here the lower courts erred by failing to observe the principle that if both parties to a contract have been under a misapprehension about a fact that dramatically affects the contract’s value—such as Rose’s fecundity—the contract can be held to be void. However, as students usually learn while discussing this case, if just one side knows a crucial fact, the law is not so simple. The retrial in this case, taking the mutual mistake into account, let Walker keep Rose.

The late Brainerd Currie, a professor at Duke University School of Law, memorialized the case in a somber poem, after Coleridge’s “Christabel,” that is often quoted in casebooks. It reads, in part: “A dismal specter haunts this wake—/ The law of mutual mistake;/ And even the reluctant drone/ Must cope with Rose of Aberlone./ She rules the cases, she stalks the page/ Even in this atomic age. … / That she will turn up in some set of facts is/ Almost as certain as death and taxes:/ For students of law must still atone/ For the shame of Rose of Aberlone.”

A man ran for a train as it left the station. Two guards pulled and pushed him aboard. In the confusion, he dropped a package he was carrying. Containing fireworks, the package exploded. The shock knocked down some scales at the other end of the platform, and they injured Mrs. Palsgraf. Mrs. Palsgraf sued the railroad for negligence and won; the railroad appealed. On appeal, the judgment was reversed and Mrs. Palsgraf’s complaint was dismissed.

This provides a suitably cloudy introduction to the legal gray area of “proximate cause.” Theoretically, every negligent act can give rise to an infinite string of consequences, but it would be both unfair and impossible to try to compensate everyone even remotely wronged. Proximate cause—one of many legal concepts that are simply matters of degree—is the sometimes vague notion that an injury must have been the “proximate” result of a negligent act to be grounds for redress.

Benjamin Cardozo, chief judge of the New York State Court of Appeals, used the case to try to create a new method for determining proximate cause. In his majority opinion he argued that liability extended to whomever the wrongdoer had a duty to protect, and that in pushing a man onto a moving train—however negligently —the conductors had no duty to think of Mrs. Palsgraf across the platform. The dissenting opinion embodies the view still prevalent today: If you unreasonably endanger people, you are liable for all proximate consequences regardless of any notion of duty. And Rembar points out, “Cardozo’s test is still a matter of degree.”

George Hawkins’s right hand was severely scarred from burns. Dr. Edward McGee offered to perform a skin graft, which he said would give Hawkins a “hundred percent perfect hand.” After the operation, the skin, which had been taken from Hawkins’s chest, grew “matted” hair. Hawkins sued McGee for breach of contract and won; McGee succeeded in having the award reduced. Then Hawkins appealed. On appeal, a new trial was ordered.

This is the case with which Professor Kingsfleld opens his harrowing contracts course in the novel and movie The Paper Chase. And it’s a good first case, for the real issue in it is one of the most basic matters of contract law. The lower-court judge had instructed the jury to fix restitution on the basis of “what pain and suffering [Hawkins] has been made to endure and what injury he has sustained over and above the injury that he had before.” That might have been a proper charge in a torts case—torts are wrongs like negligence; in Rembar’s words, torts are “essentially what’s left when you take away criminal law, contract law, divorce law, property law, and every other field of law that bears a name of its own.” Hawkins v. McGee, since it concerns the doctor’s promise as a legal guarantee, is a contract matter. And in a contract dispute, in American and English law, the only proper basis for fixing recovery is the difference in value between what was promised and what, if anything, was delivered. Suffering is irrelevant.

In this case, the question ultimately was academic. Hawkins and McGee settled out of court.

Charles Summers, Harold Tice, and Ernest Simonson went hunting. Tice and Simonson shot simultaneously at a quail in Summers’s direction, and one of their bullets hit Summers in the eye. He sued them for negligence and won; they appealed, claiming that they could not both be guilty for one bad shot. On appeal, the judgment against them was affirmed.

“This case is on the surface illogical,” says Rembar “If two or more people act in concert in committing’ tort, you can sue either or both for the full amount. But here the defendants, though each was negligent, acted independently. Yet the court applies the ‘concert’ rule. What it is really doing is invoking what one might call the counter-principle principle. If the settled law leads to what the court feels is an outrageous result, it will sometimes disregard principle. The ‘sometimes’ is important, though. In general, principles are followed, even when the result is harsh. Otherwise the law would be chaotic. Just how outrageous the result must be to lead a court to abandon a principle is part of the art of judging, and part of the art of the lawyer in giving advice to his client.”

This case has become a well-known legal precedent, establishing what is called the Doctrine of Summers v. Tice. Recently there have been efforts to apply it to cases in which it is impossible to determine what brand of a dangerous medication a victim took decades before. However, almost all courts have declined to extend the doctrine that far.

Brian Dailey, age five, was visiting Naomi and Ruth Garratt, adults. Ruth Garratt prepared to sit down in a lawn chair, and Brian pulled it away and sat in it himself. She fell and broke her hip and sued him for battery. The trial court dismissed her case; she appealed. On appeal, the case was remanded to the trial court for clarification.

“Undoubtedly this case is taught partly because the pulled chair is a classic symbol of sadistic humor,” says Rembar. “But also it brings up the problem of intent that comes up so often both in the field of torts and in criminal law. It’s a good case for a professor to play around with by varying the facts.” The lower court had accepted Brian’s testimony that he had no intention of actually hurting the arthritic Ruth Garratt, that she hadn’t begun to sit down when the incident began, and that he had even tried to put the chair back under her as she sat. The appeals court—after confirming that “when a minor has committed a tort with force he is liable to be proceeded against as any other person would be”—explained that under common law, Brian did not have to intend to hurt Ruth Garratt to be liable; he had only to know with “substantial certainty” that his intentional action would cause her to hit the ground, which would be a harmful result. Thus the issue was not Brian’s motivation or timing, but simply whether he knew that the frail Ruth Garratt would try to sit.

When the case was returned to the trial judge for real consideration of the facts, he entered a judgment of eleven thousand dollars against Brian.